The disclosure relates to a piston for an internal combustion engine configured as a single-piece cooling duct piston in accordance with its production and which comprises a piston upper part and a piston lower part that are connected in a material-to-material manner by welding.
U.S. Pat. No. 6,155,157 shows a cooling duct piston with two components that can be produced separately which are subsequently joined together in a material-to-material manner by means of a friction welding process to form a single-piece cooling duct piston. DE 10 2004 061 778 A1 relates to a cooling duct piston consisting of an upper part and a lower part that are supported by matching joining webs running rotationally symmetrically and spaced apart radially. Friction welding of joining zones achieves a material-to material connection of the inner joining webs. The radially outer joining webs are then joined using a separate welding procedure.
A piston is known from DE 10 2009 015 820 A1 that includes a combustion chamber recess introduced centrally in the piston crown, an inner cooling space and an outer cooling duct that are correspondingly arranged rotationally symmetrically. The piston upper part and the piston lower part are supported by joining webs, where joining zones of the joining webs are connected in a material-to-material manner by multi-orbital friction welding. The wall thickness of the joining webs running rotationally symmetrically changes over their longitudinal length.
In multi-orbital friction welding, the individual components are clamped, pressed against each other and oscillated. The joining partners are moved in circular orbital motions to create frictional heat and preferably oscillate in anti-phase whereby frictional energy is introduced into the joining zones. In contrast to previous friction welding processes, weld times are shortened and subsequent processes reduced using multi-orbital friction welding. Since the materials are joined in a plastic state with multi-orbital friction welding, the temperature level is below the melting temperatures of conventional friction welding.
It would be desirable to create a weight-optimized piston with improved cooling that can withstand higher thermal loads.